Spring damper units of the aforementioned type are used in automotive technology to damp relative movements between two vehicle parts and to control a spaced disposition between the vehicle parts. Modern spring damper units in motor vehicles render it possible to control the level to compensate for the load and to adjust the height of vehicles in order to be able to ensure the optimum ground clearance constantly even in the most varied of load states and the most varied road conditions. An adjusting device is usually provided for this purpose, which adjusting device operates between the spring damper unit and the vehicle body and/or the vehicle wheel. Alternatively, the adjusting device can operate inside the spring damper unit.
The two variants mentioned hereinabove, however, are encumbered with disadvantages that adversely affect the travel comfort. If the adjusting device operates between the spring damper unit and the vehicle body or the vehicle wheel, then, as the load compensation is performed, the stroke lengths of the extension stage and the compression stage of the damper component of the spring damper unit are reduced. If the adjusting device operates inside the spring damper unit, then, as a height adjustment is performed, one spring stroke is shortened at the expense of the other spring stroke. This effect then occurs, for example, if a vehicle is set to a higher level due to a poor road surface. During an extension movement, the damper component then impacts against its upper allocated stop earlier in comparison to a state where no height adjustment has been performed. Consequently, when travelling with an increased ground clearance, the travel comfort is noticeably impaired.